The present invention relates generally to a system and apparatus for automated tank cathodic protection/corrosion monitoring. More specifically, the present invention is an automated tank cathodic protection/corrosion monitoring system.
Internal, submerged, metallic surfaces of liquid-containing tanks and reservoirs are subject to corrosion due to electrochemical reactions between the metallic surfaces and the liquid medium they are in contact with. Cathodic protection systems are installed in tanks and reservoirs to limit the amount of corrosion occurring on submerged metallic surfaces of the tanks and reservoirs. Tank and reservoir owners/operators often monitor the performance of the cathodic protection system and the level of corrosion protection achieved from the cathodic protection system in order to verify the system's functionality and ensure the submerged metallic structures are properly protected from corrosion.
The cathodic protection systems in tanks are monitored by measuring the potential of the tank utilizing a high impedance voltmeter with respect to a reference electrode employed within the liquid medium. The potential measurement is representative of the condition of the submerged, metallic surfaces within a close vicinity of the location of the reference electrode. The potential measurements are then compared against criteria within current industry standards to determine whether or not the structure is adequately protected at the measurement location.
Known methods for monitoring tank cathodic protection systems include permanent, stationary reference electrodes installed within the tanks as well as portable reference electrodes that can be inserted manually into the tank. Both existing methods require a technician be onsite to collect the data utilizing a voltmeter/digital multimeter and either the permanent, stationary reference electrodes fixed at known positions in the tank, or the portable reference electrode.
The permanent, stationary reference electrodes often become contaminated from long-term exposure to the liquid medium within the tank. This contamination lessens the accuracy, consistency, and reliability of the reference electrodes over time. In most cases, portable reference electrodes are utilized in lieu of the permanent, stationary reference electrodes because of this reason. The potential measurements are also a function of the distance between the reference electrode and possible damage on internal coatings adding variability to measurements.
The existing tank cathodic protection system monitoring methods are also limited by lack of access to all of the internal submerged surfaces of the tank. Measurements may often only be collected at specific points within the tank either where the permanent, stationary reference electrodes are installed or where the technician has roof access to lower a portable reference electrode into the tank.